A mosaic of images in blue, green and red light of the Whirlpool Galaxy, Messier 51, and its companion Galaxy, Messier 51B, The Galaxy is 24 million light years from Earth, and the image covers approximately 100,000 light years across. At each wavelength, twenty-two individual images , acquired by the Sloan Digital Sky Survey (SDSS), have been aggregated into the mosaic by the Montage image mosaic engine. The mosaic is shown as generated by the engine, with no artificial enhancements of features, and is ready for scientific analysis. Superposed on the mosaic are a coordinate grid, the locations of infrared point sources measured by the Two Micron All-Sky Survey (2MASS) and the outlines of images made by the Spitzer Space Telescope. Software such as Montage now allows astronomers to create large scale images such as these and to superpose information about data measured at different wavelengths as the starting point in their scientific investigations. For the technically minded: The SDSS images have been reprojected to a common grid and background-matched for seamless co-addition. The stretches in each band are the Montage defaults based on a custom gaussian histogram-equalization algorithm. The coordinate grid is Equatorial J2000. Montage is funded by the National Science Foundation (NSF). Bruce Berriman (PI), John Good (Software Architect).